JournalTOCs School of Mathematical and Computer Sciences Heriot-Watt University Edinburgh, EH14 4AS, UK Email: journaltocs@hw.ac.uk Tel: +00 44 (0)131 4513762  Your IP address: 18.206.48.243 | ||||||
JournalTOCs School of Mathematical and Computer Sciences Heriot-Watt University Edinburgh, EH14 4AS, UK Email: journaltocs@hw.ac.uk Tel: +00 44 (0)131 4513762 Your IP address: 18.206.48.243 | ||||||
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Objective: Phenytoin is commonly prescribed to prevent postoperative seizures. Despite the rarity of the CYP2C9 genetic polymorphism, which may result in poor phenytoin metabolism, in the Thai population, the authors report a case of phenytoin toxicity in a patient with poor metabolism administered with a standard dose of phenytoin.Case Report: A 58-year-old Thai woman presented to the outpatient clinic with a 2-day history of nausea, vomiting, and dizziness. She underwent craniotomy for tumor removal 2 weeks after being diagnosed with tuberculum sellae meningioma. After the surgery, she was prescribed 300 mg of phenytoin daily to prevent seizures. During the physical examination, ataxia, horizontal nystagmus, and cerebellar abnormalities were observed, with an initial serum phenytoin concentration of 58.85 mg/L. The brain imaging results were unremarkable. Omeprazole was the only recognized drug interaction; however, it is highly unlikely to account for this condition. Pharmacogenetic investigation of CYP2C9 revealed a homozygous CYP2C9*3/*3 mutation, which is indicative of suboptimal drug metabolism and can reduce phenytoin metabolism by 50%. This patient was administered repeated dosages of activated charcoal over the course of 2 days. Her symptoms eventually subsided, with the phenytoin levels dropping to 29.51 mg/L.Conclusions: In the absence of an overdose history or drug–drug interaction, CYP2C9 polymorphism should be suspected in patients with phenytoin toxicity. In such situations, the phenytoin dosage must be decreased and monitored closely.
Background: Gentamicin is used to treat severe infections and has a small therapeutic window. This study aimed to optimize the dosing strategy of gentamicin in intermittently hemodialyzed patients by simulating concentration–time profiles during pre- and postdialysis dosing, based on a published pharmacokinetic model.Methods: Pharmacokinetic simulations were performed with virtual patients, including septic patients, who were treated with gentamicin and received weekly hemodialysis with an interval of 48 h–48 h–72 h. The following dosing regimens were simulated: for nonseptic patients, 5 mg/kg gentamicin was given 1 h or 2 h before dialysis or a starting dose of 2.5 mg/kg and a maintenance dose of 1.5 mg/kg immediately after dialysis were given; for septic patients, 6 mg/kg gentamicin was given 1 h or 2 h before dialysis or a starting dose of 3 mg/kg and a maintenance dose of 1.8 mg/kg immediately were given after dialysis. The mean maximum concentration (Cmax), area under the curve (AUC)24 h, and target attainment (TA) of pharmacodynamic targets were calculated and compared. The following targets were adopted from the literature: Cmax>8 mg/L and 70 mg·h/L and 8 mg/L, 100% for 70 mg·h/L, and 45% for 8 mg/L, 40% for 70 mg·h/L, and 77% for 8 mg/L and acceptable TA of Cmax 70 mg·h/L, and AUC24 h
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Abstract: The authors present a case of severe multidrug intoxication following massive ingestion of lithium, nortriptyline, aripiprazole, lorazepam, and temazepam. After initial treatment, serum lithium levels decreased significantly. However, 28 hours post ingestion, recurrent elevated lithium levels were observed, and serum lithium level increased 0.71 mmol/L in 12 hours. The intensivist consulted a hospital pharmacist about this. After administering clearance-inducing therapy using continuous venovenous hemodialysis, the lithium level was reduced to a long-lasting nontoxic level. The occurrence of secondary elevation in lithium levels exceeding the toxic limit in cases of massive ingestion of lithium tablets, whether in combination with anticholinergic drugs, should be anticipated. Close monitoring and prompt initiation of clearance-inducing therapy can improve clinical outcomes.
Background: Recently, several studies have assessed the effects of therapeutic drug monitoring of frequently prescribed beta-lactam antibiotics, for which they were quantified in human plasma samples. Beta-lactams are considered unstable, leading to extra challenges in quantification. Therefore, to ensure sample stability and minimize sample degradation before analysis, stability studies are crucial. This study investigated the stability of 10 frequently used beta-lactam antibiotics in human plasma at relevant storage conditions for clinical use.Methods: Amoxicillin, benzylpenicillin, cefotaxime, ceftazidime, ceftriaxone, cefuroxime, flucloxacillin, imipenem, meropenem, and piperacillin were analyzed using ultraperformance convergence chromatography tandem mass spectrometry and liquid chromatography tandem mass spectrometry. Their short-term and long-term stabilities were investigated by measuring quality control samples at low and high concentrations against freshly prepared calibration standards. Measured concentrations at each time point were compared with the concentrations at T = 0. Antibiotics were considered stable if recovery results were between 85% and 115%.Results: Short-term stability results indicated ceftriaxone, cefuroxime, and meropenem to be stable up to 24 hours at room temperature. All evaluated antibiotics, except imipenem, were stable on ice in a cool box for 24 hours. Amoxicillin, benzylpenicillin, and piperacillin were stable for 24 hours at 4–6°C. Cefotaxime, ceftazidime, cefuroxime, and meropenem were stable at 4–6°C up to 72 hours. Ceftriaxone and flucloxacillin were stable for 1 week at 4–6°C. Long-term stability results showed that all antibiotics were stable up to 1 year at −80°C, except imipenem and piperacillin, which were stable for 6 months at −80°C.Conclusions: Plasma samples for amoxicillin, benzylpenicillin, cefotaxime, ceftazidime, flucloxacillin, and piperacillin may be stored for a maximum of 24 hours in a cool box. Refrigeration is suitable for plasma samples of amoxicillin, benzylpenicillin, meropenem, and piperacillin for up to 24 hours and cefotaxime, ceftriaxone, ceftazidime and cefuroxime for 72 hours. Plasma samples for imipenem should be frozen directly at −80°C. For long-term storage, plasma samples can be stored at −80°C for a maximum of 6 months for imipenem and piperacillin and 12 months for all other evaluated antibiotics.
Background: Pompe disease is a rare genetic disorder caused by a deficiency of a lysosomal enzyme called acid alpha-glucosidase and is classified into infantile and late-onset forms. Since 2006, an enzyme replacement therapy involving alglucosidase alfa has been available. In 2021, a new enzyme replacement therapy involving avalglucosidase alfa demonstrated improved clinical benefits. In this article, the authors describe the pharmacokinetics of avalglucosidase alfa using a population pharmacokinetic approach.Methods: The population pharmacokinetic model was developed using a data set that included 75 patients and 2042 plasma drug concentrations determined through enzymatic activity assay from 3 studies (phases I/II and III) and involved 3 dose levels (5, 10, and 20 mg/kg). The analysis was performed using NONMEM software.Results: Two sequences were observed in the plasma drug concentration profile: the first kinetic driving exposure, and after 12 hours postdose, a slight rebound addressing very low concentrations that lasted up to 2 weeks. Following model screening, a model with a central compartment with parallel linear and nonlinear elimination and 2 concatenated peripheral compartments was proposed. A putative back-redistribution of a marginal fraction of the drug from the second peripheral compartment to the central compartment may explain the slight rebound in concentration. The final model's mean bias and precision for individual predictions were −2.66% and 30.7%, respectively, and −0.433% and 38.9%, respectively, for population predictions.Conclusions: A concatenated 3-compartment model was developed to describe the avalglucosidase alfa concentrations in patients with late-onset Pompe disease. None of the covariates tested could explain the interindividual variability.
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Background: Orelabrutinib is a second-generation Bruton tyrosine kinase inhibitor that improves the management of B-cell malignancies. The objective of this study was to develop and validate an LC-MS/MS method for quantifying orelabrutinib in human plasma.Methods: Plasma samples were processed using acetonitrile to precipitate proteins. Ibrutinib-d5 was used as the internal standard. The mobile phase comprised 10 mM ammonium formate containing 0.1% formic acid and acetonitrile (62:38, vol/vol). The multiple reaction monitoring transitions at m/z = 428.1 → 411.2 and 446.2 → 309.2 were selected for orelabrutinib and ibrutinib-d5, respectively, after ionization in the positive mode.Results: Total runtime was 4.5 minutes. The validated curve ranges were 1.00–500 ng/mL. This method exhibited acceptable selectivity, dilution integrity, matrix effects, and recovery. Interrun and intrarun accuracy ranged from −3.4% to 6.5%, and interrun and intrarun precision was between 2.8% and 12.8%. Stability was studied under different conditions. The incurred sample reanalysis demonstrated good reproducibility.Conclusions: The LC-MS/MS method provided a simple, specific, and rapid quantification of orelabrutinib in the plasma of patients with mantle cell lymphoma or chronic lymphocytic leukemia/small lymphocytic lymphoma. The results indicated that orelabrutinib exhibits large variability between individuals and should be prudently used in combination with CYP3A4 inhibitors.
Background: Despite its federally restricted status, cannabis is widely used medicinally and recreationally. The pharmacokinetics (PK) and central nervous system (CNS) effects of tetrahydrocannabinol (THC), the major psychoactive cannabinoid, are not well understood. The objective of this study was to develop a population PK model of inhaled THC, including sources of variability, and to conduct an exploratory analysis of potential exposure–response relationships.Methods: Regular adult cannabis users smoked a single cannabis cigarette containing 5.9% THC (Chemovar A) or 13.4% THC (Chemovar B) ad libitum. THC concentrations in whole blood were measured and used to develop a population PK model to identify potential factors contributing to interindividual variability in THC PK and to describe THC disposition. Relationships between model-predicted exposure and heart rate, change in composite driving score on a driving simulator, and perceived highness were evaluated.Results: From the 102 participants, a total of 770 blood THC concentrations were obtained. A two-compartment structural model adequately fit the data. Chemovar and baseline THC (THCBL) were found to be significant covariates for bioavailability, with Chemovar A having better THC absorption. The model predicted that heavy users—those with the highest THCBL—would have significantly higher absorption than those with lighter previous use. There was a statistically significant relationship between exposure and heart rate, and exposure and perceived highness.Conclusions: THC PK is highly variable and related to baseline THC concentrations and different chemovars. The developed population PK model showed that heavier users had higher THC bioavailability. To better understand the factors affecting THC PK and dose–response relationships, future studies should incorporate a wide range of doses, multiple routes of administration, and different formulations relevant to typical community use.
Background: Meropenem is a carbapenem antibiotic often used in pediatric intensive care units due to its broad spectrum of activity. Therapeutic drug monitoring (TDM) is a useful tool to increase the effectiveness of meropenem by adjusting the dose based on plasma levels; however, the relatively large sample volume required for TDM can limit its use in children. Therefore, this study aimed to determine meropenem concentrations and consequently perform TDM effectively using the smallest possible sample volume. Volumetric absorptive microsampling (VAMS) is a sampling technology developed to collect a small, precise volume of blood. For the applicability of VAMS in TDM, plasma concentrations must be reliably calculated from whole blood (WB) collected by VAMS.Methods: VAMS technology using 10 µL of WB was evaluated and compared with EDTA-plasma sampling. High-performance liquid chromatography with UV detection was applied to quantify meropenem in VAMS and plasma samples after the removal of proteins by precipitation. Ertapenem was used as the internal standard. Samples were collected simultaneously from critically ill children receiving meropenem using VAMS and traditional sampling.Results: It was found that no consistent factor could be determined to calculate meropenem plasma concentrations from the WB, indicating that VAMS was not reliable in the TDM of meropenem. Therefore, to reduce the required sample amount in pediatric patients, a method for quantifying meropenem from 50 µL of plasma with a lower limit of quantification of 1 mg/L was developed and successfully validated.Conclusions: A simple, reliable, and low-cost method was established using high-performance liquid chromatography–UV to determine the concentration of meropenem in 50 µL of plasma. VAMS using WB does not seem to be suitable for TDM of meropenem.
Background: This study aimed to compare the achievement of pharmacokinetic–pharmacodynamic (PK-PD) exposure targets for vancomycin using a newly developed dosing guideline with product-information-based dosing in the treatment of adult patients with serious infections.Methods: In silico product-information- and guideline-based dosing simulations for vancomycin were performed across a range of doses and patient characteristics, including body weight, age, and renal function at 36–48 and 96 hours, using a pharmacokinetic model derived from a seriously ill patient population. The median simulated concentration and area under the 24-hour concentration–time curve (AUC0-24) were used to measure predefined therapeutic, subtherapeutic, and toxicity PK-PD targets.Results: Ninety-six dosing simulations were performed. The pooled median trough concentration target with guideline-based dosing at 36 and 96 hours was achieved in 27.1% (13/48) and 8.3% (7/48) of simulations, respectively. The pooled median AUC0-24/minimum inhibitory concentration ratio with guideline-based dosing at 48 and 96 hours was attained in 39.6% (19/48) and 27.1% (13/48) of simulations, respectively. Guideline-based dosing simulations yielded improved trough target attainment compared with product-information-based dosing at 36 hours and significantly less subtherapeutic drug exposure. The toxicity threshold was exceeded in 52.1% (25/48) and 0% (0/48) for guideline- and product-information-information-based dosing, respectively (P < 0.001).Conclusions: A Critical care vancomycin dosing guideline appeared slightly more effective than standard dosing, as per product information, in achieving PK-PD exposure associated with an increased likelihood of effectiveness. In addition, this guideline significantly reduced the risk of subtherapeutic exposure. The risk of exceeding toxicity thresholds, however, was greater with the guideline, and further investigation is suggested to improve dosing accuracy and sensitivity.
Background: This study aimed to assess the effect of perampanel dose, age, sex, and antiseizure medication cotherapy on steady-state free-perampanel concentration in children with refractory epilepsy, as well as the relationship between inflammation and the pharmacokinetics of perampanel.Methods: This prospective study in China included 87 children with refractory epilepsy treated with adjunctive perampanel therapy. Free and total perampanel concentrations in plasma were determined using liquid chromatography–tandem mass spectrometry. Free-perampanel concentration was compared among patients with various potential influencing factors.Results: A total of 87 pediatric patients (44 female children) aged 2–14 years were enrolled. The mean free-perampanel concentration and free concentration-to-dose (CD) ratio in plasma were 5.7 ± 2.7 ng/mL (16.3 ± 7.7 nmol/L) and 45.3 ± 21.0 (ng/mL)/(mg/kg) [129.6 ± 60.1 (nmol/L)/(mg/kg)], respectively. The protein binding of perampanel in plasma was 97.98%. A linear relationship was observed between perampanel dose and free concentration in plasma, and a positive relationship was found between the total and free-perampanel concentrations. Concomitant use of oxcarbazepine reduced the free CD ratio by 37%. Concomitant use of valproic acid increased the free CD ratio by 52%. Five patients had a plasma high-sensitivity C-reactive protein (Hs-CRP) level of>5.0 mg/L (Hs-CRP positive). The total and free CD ratios of perampanel were increased in patients with inflammation. Two patients with inflammation developed adverse events, which disappeared as the Hs-CRP level returned to normal, and neither required perampanel dose reduction. Age and sex did not influence the free-perampanel concentration.Conclusions: This study found complex drug interactions between perampanel and other concomitant antiseizure medications, providing valuable information to enable clinicians to apply perampanel in the future reasonably. In addition, it may be important to quantify both the total and free concentrations of perampanel to assess complex pharmacokinetic interactions.
Background: Therapeutic drug monitoring (TDM) is a decision-making tool for optimizing the use of certain therapies. In this article, the authors review the role of proactive TDM of biological agents in patients with inflammatory bowel disease (IBD) and other immune-mediated inflammatory diseases (IMID). They also discuss the future of TDM as a component of personalized medicine from the clinical laboratory perspective.Methods: This narrative review originated from proceedings of the fifth biannual Challenges in Therapeutic Drug Monitoring seminar and was supplemented by additional literature identified at various stages of critical review.Results: Proactive TDM aims to achieve adequate concentrations of biological drugs, such that patients attain and maintain an optimal treatment response. Proactive TDM may also have a role in de-escalating anti–tumor necrosis factor therapy in patients in clinical remission and in optimizing infliximab monotherapy as an alternative to combination therapy with an immunomodulator. A major proactive TDM application is in pediatric patients with IBD. Achieving mucosal healing in children with IBD requires that infliximab or adalimumab concentrations are monitored early during induction therapy, with dose modifications guided by the timing (week) of measurement. Recent innovations in biological therapy include international standards for infliximab and adalimumab for the global harmonization of bioactivity and monotest devices with an accuracy equivalent to that of conventional enzyme-linked immunosorbent assays and quicker turnaround times.Conclusions: Despite several knowledge gaps regarding proactive TDM of anti–tumor necrosis factor therapy in patients with IMID, growing evidence suggests that it is associated with better outcomes than empiric optimization and/or reactive TDM in IBD. Enhanced pharmacokinetic modeling to predict drug exposure and patient genotyping for the precise application of proactive TDM are considered key elements to optimize biological therapy in the future.
Background: Paroxetine is a selective serotonin reuptake inhibitor metabolized by cytochrome P450 (CYP)2D6. Only small-scale studies have reported the impact of CYP2D6 genotype on paroxetine exposure, and international guidelines differ in their recommendations on whether paroxetine should be administered according to CYP2D6 genotype. To clarify this issue, the aim of the present study was to investigate the impact of CYP2D6 genotype on paroxetine serum concentration in a large population of patients after adjusting for CYP2C19 genotype, age, and sex.Methods: Patients from a therapeutic drug monitoring database with records on their paroxetine serum concentrations and CYP2D6 and CYP2C19 genotyping between 2010 and 2021 were included in the study. The impact of CYP2D6 and CYP2C19 genotypes, age, and sex on the paroxetine concentration-to-dose (C/D) ratio was investigated by multiple linear regression analysis. Patients treated with relevant CYP inhibitors or inducers were excluded.Results: In total, 304 patients were included in the study: 17 CYP2D6 poor metabolizers (PMs), 114 intermediate metabolizers (IMs), 168 extensive metabolizers (EMs), and 5 ultrarapid metabolizers. Multiple linear regression analysis showed that CYP2D6 IMs and PMs had 2.2-fold and 3.8-fold higher paroxetine C/D-ratios than extensive metabolizers, respectively (P < 0.001). Patients who were CYP2C19 IMs (n = 70) or PMs (n = 13) had 1.6-fold higher paroxetine C/D ratio than extensive metabolizers (P = 0.04). An age ≥65 years was associated with a 2.9-fold increased C/D ratio (P < 0.001), whereas sex was not significantly associated with paroxetine exposure.Conclusions: The present study showed that CYP2D6 genotype is of significant importance for paroxetine dose adjustments. For CYP2D6 PMs, 25% of the regular paroxetine starting dose may be sufficient, whereas CYP2D6 IMs could receive 50% of the regular dosage. This well-powered study shows that the guidelines should consider the importance of CYP2D6 genotype for personalized dosing of paroxetine.
Background: In recent years, multiple population pharmacokinetic models have been developed for drugs such as tobramycin that need therapeutic drug monitoring. Some of these models have been used to develop a priori dosing regimens for their respective populations. However, these dosing regimens may not apply to other populations. Therefore, this study aimed to evaluate tobramycin population pharmacokinetic models in critically ill patients and establish an adequate dosing regimen.Methods: Evaluated models were identified from a literature review of aminoglycoside population pharmacokinetic models in critically ill patients. After retrospective data collection in 2 Quebec hospitals, external evaluation and model re-estimation were performed with NONMEM (v7.5) to assess imprecision and bias values. Dosing regimens were simulated and compared between the best-performing model and its re-estimated counterparts.Results: None of the 3 evaluated models showed acceptable imprecision or bias values in the data sets of the 19 patients. Similar percentages of target attainment were obtained for the original and re-estimated models after the dosing regimen simulations.Conclusion: Although the predictive performance evaluation criteria were inadequate, the original and re-estimated models yielded similar results. This raises the question of what a priori bias and imprecision thresholds should be defined as acceptable for the external evaluation of models to be applied in clinical practice. Studies evaluating the impact of these thresholds are needed.
Background: Amisulpride, a second-generation atypical antipsychotic drug, was first marketed in Europe in the 1990s. This study aimed to provide a reference for the clinical application of amisulpride. The effects of age, sex, or specific comedications on amisulpride concentrations in Chinese patients with schizophrenia in the real world were investigated.Methods: A retrospective study was conducted of data on amisulpride based on the therapeutic drug monitoring service database at the Zigong Affiliated Hospital of Southwest Medical University.Results: Based on the inclusion criteria, 195 plasma samples from 173 patients (67.05% female and 32.95% male patients) were included for in-depth analysis. The median daily dose of amisulpride was 400 mg/d, median plasma concentration was 457.50 ng/mL, and median concentration/dose (C/D) ratio was 1.04 ng/mL/mg/d. The daily dose of amisulpride positively correlated with measured steady-state plasma concentrations. A significant difference was observed in the subgroup analysis of the combination with valproic acid, zopiclone, or aripiprazole on plasma concentrations. Combining amisulpride with these drugs increased the C/D ratios by 0.56-, 2.31-, and 0.77-fold, respectively. After adjusting for age, the median C/D ratio was found to be significantly different between female and male patients. However, no significant differences in daily dose, plasma concentration, and C/D ratio were noted with respect to sex and age of the patients.Conclusions: Sex differences were inferred for the first time in this study, with differential effects on daily dose, steady-state plasma concentration, and C/D ratio associated with the population. In the included study samples, blood concentrations were distributed in the range of 223.25–823.55 ng/mL, which perhaps needs to be evaluated in line with the reference range of ammonia–sulfur ratios in the Chinese population.
Background: The Immunosuppressant Bayesian Dose Adjustment web site aids clinicians and pharmacologists involved in the care of transplant recipients; it proposes dose adjustments based on the estimated area under the concentration–time curve (AUCs). Three concentrations (T20 min, T1 h, and T3 h) are sufficient to estimate mycophenolic acid (MPA) AUC0–12 h in pediatric kidney transplant recipients. This study investigates mycophenolate mofetil (MMF) doses and MPA AUC values in pediatric kidney transplant recipients, and target exposure attainment when the proposed doses were followed, through a large-scale analysis of the data set collated since the inception of the Immunosuppressant Bayesian Dose Adjustment web site.Methods: In this study, 4051 MMF dose adjustment requests, corresponding to 1051 patients aged 0–18 years, were retrospectively analyzed. AUC calculations were performed in the back office of the Immunosuppressant Bayesian Dose Adjustment using published Bayesian and population pharmacokinetic models.Results: The first AUC request was posted>12 months posttransplantation for 41% of patients. Overall, only 50% had the first MPA AUC0–12 h within the recommended 30–60 mg.h/L range. When the proposed dose was not followed, the proportion of patients with an AUC in the therapeutic range for MMF with cyclosporine or tacrolimus at the subsequent request was lower (40% and 45%, respectively) than when it was followed (58% and 60%, respectively): P = 0.08 and 0.006, respectively. Furthermore, 3 months posttransplantation, the dispersion of AUC values was often lower at the second visit when the proposed doses were followed, namely, P = 0.03, 0.003, and 0.07 in the 4 months–1 year, and beyond 1 year with 6-month periods between both visits, respectively.Conclusions: Owing to extreme interindividual variability in MPA exposure, MMF dose adjustment is necessary; it is efficient at reducing such variability when based on MPA AUC.
Background: Therapeutic drug monitoring of mesalazine (5-ASA) in patients with ulcerative colitis is unavailable. Mucosal 5-ASA concentrations are assumed to be higher during remission, but biopsy is not practical. Therefore, we investigated the feasibility of measuring mesalazine levels in feces. To explore the potential role of fecal mesalazine measurements in therapeutic drug monitoring, we compared the dry fecal concentration and daily fecal excretion of 5-ASA and its metabolite N-acetyl-5-ASA in patients with ulcerative colitis with active and quiescent disease.Methods: Adults with ulcerative colitis on oral mesalazine and scheduled for colonoscopy were eligible for inclusion in this cross-sectional study. Stool and urine samples were collected for 48 and 24 hours, respectively, and rectal biopsies were performed. (N-acetyl-)5-ASA was measured using mass spectrometry. Biochemically active disease was defined as a fecal calprotectin level above 100 mcg/g and endoscopically active disease as any activity following the endoscopic Mayo score (≥1).Results: Approximately 28 patients were included in the study. Daily fecal excretion of (N-acetyl-)5-ASA did not differ between patients with (n = 13) and without (n = 15) endoscopically active disease [median 572 mg/d versus 597 mg/d (P = 0.86) for 5-ASA and 572 mg/d versus 554 mg/d (P = 0.86) for N-acetyl-5-ASA]. The same applied to the fecal concentration [median 9.7 mcg/mg dry weight versus 10.3 (P = 0.53) and 12.0 versus 9.9 (P = 0.89)]. The results were comparable when the biochemical disease activity definition was used. The mucosal concentrations and urinary excretion of (N-acetyl-)5-ASA did not differentiate between quiescent and active activity.Conclusions: Fecal (N-acetyl-)5-ASA measurements do not correlate with disease activity, which renders it an unsuitable tool for therapeutic drug monitoring of mesalazine.
Purpose: Vancomycin dosing remains challenging in patients receiving intermittent hemodialysis, especially in developing countries, where access to therapeutic drug monitoring and model-based dose adjustment services is limited. The objectives of this study were to describe vancomycin population PK in patients receiving hemodialysis in a Malian and French center and examine the optimal loading dose of vancomycin in this setting.Methods: Population pharmacokinetic analysis was conducted using Pmetrics in 31 Malian and 27 French hemodialysis patients, having a total of 309 vancomycin plasma concentrations. Structural and covariate analyses were based on goodness-of-fit criteria. The final model was used to perform simulations of the vancomycin loading dose, targeting a daily area under the concentration–time curve (AUC) of 400–600 mg.h/L or trough concentration of 15–20 mg/L at 48 hours.Results: After 48 hours of therapy, 68% of Malian and 63% of French patients exhibited a daily AUC of
Background: Perampanel (PER) is an oral antiepileptic drug and its concomitant use with carbamazepine (CBZ) leads to decreased PER concentrations. However, the magnitude of its influence may vary, depending on the dynamics of the enzyme induction properties of CBZ. This study aimed to develop a population pharmacokinetic (PPK) model considering the dynamics of enzyme induction and evaluate the effect of CBZ on PER pharmacokinetics.Methods: We retrospectively collected data on patient background, laboratory tests, and prescribed drugs from electronic medical records. We developed 2 PPK models incorporating the effect of CBZ-mediated enzyme induction to describe time–concentration profiles of PER using the following different approaches: (1) treating the concomitant use of CBZ as a categorical covariate (empirical PPK model) and (2) incorporating the time-course of changes in the amount of enzyme by CBZ-mediated induction (semimechanistic PPK model). The bias and precision of the predictions were investigated by calculating the mean error, mean absolute error, and root mean squared error.Results: A total of 133 PER concentrations from 64 patients were available for PPK modelling. PPK analyses showed that the co-administration of CBZ increased the clearance of PER. Goodness-of-fit plots indicated a favorable description of the observed data and low bias. The mean error, mean absolute error, and root mean square error values based on the semimechanistic model were smaller than those obtained using the empirical PPK model for predicting PER concentrations in patients with CBZ.Conclusions: We developed 2 PPK models to describe PER pharmacokinetics based on different approaches, using electronic medical record data. Our PPK models support the use of PER in clinical practice.
